Taylor allderdice



UNITED STATES TAYLOR ALLDERDIOE, OF SWISSVALE, ASSIGNOR TO THE CARNEGIESTEEL PATENT. OFFICE.

COMPANY, LIMITED, OF. PITTSBURG, PENNSYLVANIA.

PROCESS OF MANUFACTURING STEEL.

SPECIFICATION forming part of Letters Patent No. 491,035, dated January31, 1893.

Application filed February 3, 1892.

To all whom it may concern.-

Be it known that I, TAYLOR ALLDERDIOE, of Svvi'ssvale, in the county ofAllegheny and State of Pennsylvania, have invented a new and usefulImprovement in the Process of Manufacturing Steel, of which thefollowing is a full, clear, and exact description.

My invention pertains to that branch of the manufacture of steel inwhich steel is made by the Bessemer, open-hearth, or similar process,and is subsequently carburized by the addition to it of free carbon, inthe form of coke dust, graphite, Wood-charcoal, 650.; and it has for itsobject to remedy certain practical defects in the modes of adding thecarbon heretofore employed, and to provide means by which the carboncontent of the finished product can be regulated and determinedaccurately. The principal defectin methods of supplying carbon has beentheir lack of certainty. The carbon content of the product has beendependent too much upon the care and attention of the workman managingthe pouring of the steel, and has been apt to be afiected so much byaccidents as to detract materially from the value of the process and torender its successful Working largely a matter of chance.

I have made the following discoveries with reference to the addition offree carbon in the manufacture of steel :-First, that the mostsatisfactory manner in which to add the carbon is to place it in theladle in definite quantity determined by the percentage desired in theproduct, and to cause the metal to flow upon it from the furnace orconverter. Second, that there is an important advantage derived fromhaving in the ladle, before the introduction of the carbon a sufficientquantity of molten steel to cover the discharge opening controlled bythe ladle-stopper. If this is not done, the carbon is apt to settleabout the ladle-nozzle-opening, and when the stopper is lifted to teemthe contents of the ladle, the access of air to this highly heatedcarbon may cause it to explode with violence and to throw the steel fromthe top of the ladle. The danger and loss thus occasioned are veryconsiderable. The introduction of the carbon upon the layer of moltensteel is also of advantage aside from prevention of danger, in that, by

Serial No. 420,219. (No specimens.)

keeping the carbon from direct contact with lining is largely prevented,so that Iam enabled to secure greater certainty of results in subsequentcasts in the same ladle. The thorough mixture of the car-bon by thechurnis also enhanced by thus interposing the carbon between the firstintroduced layer ofs'teel this WayI getactual contact of every portionof the steel with the carburizin'g agent. "Third, that the best and mostcertain'results are attained when the carbon, in measured quantity, isput into a combustible or easily-fusible case, and such case is throwninto the ladle (preferably upon a bottom steel layer) and the steel thenpoured upon it. Loss of the carbon from dissipation by the strongcurrents of air and gas induced in the ladle by pouring of the steel isthus avoided, and by reason of the consequent greater certainty ofpredetermination of the degree of carburization which will be eifectedby a given carbon-addition, the process is brought to the highestperfection yet attained. In practice it will be found that the mostconvenient form of casein which to introduce the carbon is a paper bag,such as those used for containing flour, but easily destructible boxesmade of paper, thin wood, or easily fusible metal may be employed withlike advantages. Each of these discoveries above recited forms anindividual part of my invention, and is made the basis of separate claimin this application, each claim being unlimited by conditions andqualifications peculiar to other claims.

I shall now describe my invention as heretofore practiced by'me with thebest results: After the metal has been treated in the usual manner inthe open-hearth furnace, or Bessemer converter, and is brought therebyinto proper condition for recarburization and final addition ofmanganese, &c., I run into the ladle or other vessel intended to receivethe molten steel, a sufficient quantity of the steel to cover the nozzle(discharge opening), generally introducing thus a layer of steel of fromthree to six inches in depth. Then, before introducing the remainder ofthe steel, I

the bottom of the ladle," its adherence to' the ing action of theincoming steel and the-com plete and uniform cementation of the metalandthe subsequently poured charge, since inthrow into the ladle upon themolten layer a bag or case containing a measured quantity of fineparticles of carbon, preferably in the form of Well-dried, finely-groundcoke, though wood-charcoal, anthracite coal, or graphite may besubstituted. The ordinary charge of molten steel is then poured into theladle upon the bag. The bag burns quickly, and its carbon contents,being exposed, mix with the metal and evenly carburize the same.Spiegeleisen and ferro-manganese or equivalent deoxidizing agent may beadded to the steel in the usual manner.

In thus practicing my invention, in connection with the open-hearthfurnace, one can rely with certainty on combining with the steel aboutfifty per cent, of the carbon introduced, the remainder being lost bycombustion, &c. It will be seen therefore that the capacity of the ladleand the carbon percentage of the coke or other material used beingknown, it is easy to calculate with exactness the precise quantity ofcoke which must be charged into the case in order to raise thecarbon-content of the steel from the amount ordinarily present in itwhen it is tapped from the furnace or converter (.10 of one per cent.,)to the content desired; and as this calculation may be made and the bagsfilled with carbon before they come into the hands of the lessresponsible persons who direct the tapping of the furnace, theliabilityof getting an ununiform product by careless feeding of the carbon, whichdetracts so much from the value of prior modes of operation, is absentfrom my improved process.

The following example will illustrate in detail the quantities of carbonwhich should be added to produce a given result.

Let theordinary charge of the ladle used in the process be one ton ofsteel, the content of carbon of the metal when tapped from theopen-hearth furnace, .10 of one per cent, and the carbon content desiredto be produced in the finished product by this process ofrecarburization .30 of one per cent. Then calculating on a loss of fiftyper cent, of the added free carbon, as above explained, and using cokecontaining about ninety-nine per cent of carbon, it is apparent that tocarburize the steel to the extent desired, eight pounds of ground cokeshould be charged into the case or cases to be introduced into theladles.

lrVhen using the process for recarburizing Bessemer steel, the loss ofcarbon is somewhat greater when the iron is to be highly recarburized,so that under the conditions just stated, about twelve pounds of cokedust should be added in the ladle to raise the carbon content of thesteel .20 of one per cent.

Variations in the details of working of the process will suggestthemselves to those skilled in the art.

By the term free carbon herein used, I mean solid carbon not chemicallycombined with metals.

I claim:

1. In the manufacture of steel, the improvement which consists intreating the metal in the furnace or converter for conversion intosteel, placing in a receiving vessel or ladle a definite amount of freecarbon'proper to raise the carbon content of the steel to the pointdesired, and then pouring the steel upon the same; substantially as andfor the purposes described.

2. In the manufacture of steel, the improvement which consists intreating the metal in the furnace or converter for conversion intosteel, introducing into a receiving vessel or ladle having a dischargeopening a layer of molten steel sufficient to cover the opening, thenintroducing free carbon, and pouring the steel upon the carbon;substantially as and for the purposes described.

3. In the manufacture of steel, the improvement which consists intreating the metal in the furnace orconverter for conversion into steel,introducing into a receiving vessel or ladle a' layer of molten metal,then introducing upon said layer a definite amount of free carbon properto raise the carbon content of the steel to the point desired, andpouring the steel upon the carbon; substantially as and for the purposesdescribed.

4:. In the manufacture of steel, the improvement which consists intreating the metal in the furnace or converter for conversion intosteel, placing in a receiving vessel or ladle an easily destructiblecase containing a definite amount of subdivided free carbon proper toraise the carbon content of the steel to the point desired, and pouringthe steel; substantially as and for the purposes described.

In testimony whereof I have hereunto set myhand this 30th day ofJanuary, A.D. 1892.

TAYLOR ALLDERDIOE.

Witnesses:

W. M. TAPPAN, HARRY HECKLER.

